Method of evaporation and apparatus therefor



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suns men-mar, or name; SWITZERLAND.

METHOD OF EVAPORATION AND APPARATUS THEREFOR,

Application filed September 18, 1919. Serial No. 324,590,

(cm-rm UNDER rm PROVISIONS OF THE ACT OF MARCH 3, 1921, 41 STAT. L, 1813.)

- To all whom it may concern:

Be it known that I, ELIAS WIRTH-FREY, a citizen of the Swiss Confederation, and residing at Aarau, Switzerland, have invented certain new and useful Improvements in Methods of Evaporation and Apparatus Therefor (for which I have filed application tion of salts on the heating surfaces by removing the evaporation from the proximity of these heating surfaces, which is generally done by only superhea ting the brine by contact with these surfaces and by then finishing the'evaporation in an additional chambar. In practice this is obtained b positioning the heating surfaces rather ow below the level of the liquid so that the liquid pressure prevents the evaporation on the heating surfaces and the evaporation can then only take placehig'her up; or by keepmg the passage through the heating chamby natural or artificial, for instance' ump pressure, whereby in. the heating 0 amber a superpressure-is setup which'tends to prevent theevaporat ionwithin this chamber.

All these procedures, however, render the evaporation on the heating surfaces more dificult for the reason that the liquid is under-a higher pressure than is really absolutely necessary, whichmeans that the heating steam'also mustbe under correspondingly higher-tension. Furthermore, the heat exchange with non-boiling liquids is lower than in the case of boiling liquids, so that the installation then requires more heating surface.

. According to my invention, which efiectively obviates all these drawbacks, the brine is first conducted through a heated'evaporating chamber and is then conducted for after-evaporation and separating-out of salt into a secondary chamber in which a lower pressure is maintained than in the primary evaporating chamber, and the then more or less saturated brineis finally reconducted into the primary evaporator, thus completing a cycle through the two evaporating chambers.

My invention will best be understood -when described in connection with apparatus suitable for carrying out the improved process and I have illustrated in the accom- I I panying drawing, by way of example, two

more or less 'diagrammatical sectional views of such apparatus. Like parts in the two figures are denoted by the same reference numerals.

Referring first to Fig. 1, the numeral 1 refers to a boiler, the primary evaporating chamber, withinwhich is arranged the sbeamheater 2 having the discharge pipe 20 for the exhaust of the condensate from the heater. Above the latter is located an annular liquid gutter or collector 3 of trimcated cone shape, desi ed to catch the liquid entrained by the rising vapor, and from where the li uid is carried through the conduit 4 into t e secondary or after-evaporating chamber 5. Arranged in the conduit 4 is a valve 21 to controlthe relatiye pressures in the chambers 1 and 5. The exhaust steam leaves the chambers 1 and 2 through the top vents 6 and 8 respectively. In thesecondaryevaporator 5 a pressure is maintained which is lower than that obtaining ,in the ma n eva orator 1, which allows of the 11 uid rea ily flowing through the conduit 4 into mainly in the secondeva rator. The salt is deposited in the lower unnel shaped part 5' of thechamber 5 and can be withdrawn themou'tthrough the discharge member 7. The concentrated brine is'then'led back mto the primaryevaporator throu h a conduit 9.

To assure the return flow of t e brine from the chamber 5 to the chamber 1 I preferably provide a pump 22' of any su table construction in the reflux conduit 9. This reconduction of the saturated brine into the first chamber meets with no difii'culty in spite of the pressure diiferences for the reason that the liquid column in the second chambenis materially heavier than the steam-liquid mixill) Sid

ture in the first chamber. By now again heat ing the brine it is undersaturated to some extent so that it again yields water and is then treated once more in the after-evaporator. Fresh brine is conducted from below through the suppl pipe 10 into the primary evaporator near-t e point of influx .of the pretreated brine, causing thereby a dilution of this concentrated brine and at the same time preventing or retarding the separatingout of salts within the primary evaporator.

Whilst in this arrangement the exhaust steam can be utilized, depending upon its pressure, as heating medium in preheaters or like apparatus of lower pressure than that in the chambers 1 and 5, it .is recon-' ducted in the installation illustrated in Fig. 2 into the heater. Through the conduits 6' and 8'. the exhaust steam is sucked respectively into the compressors 11 and 12, is compressed therein and then forced through the common conduit 13 into the heater 2. The compressors are so regulated that in the evaporator chambers 1 and 5 the required pressure difierence is maintained. The -perative efiect of this latter arrangement is identical to that of the firstabove described type of apparatus. Separation of the salt from the rine is prevented on the heating surfaces because on such surfaces the brine is not concentrated beyond the point of saturation, and there is thus no salt separation which might result in the formation of crusts. The. separation is effected by subjecting the brine to lower pressure in the receptacle 5. In consequence of the decrease in pressure evaporation in the receptacle will occur, but the resulting steam is used as a heating medium in the container.

5 so that all loss is eliminated.

reaaere What I claim'is:--- V V 1. The herein described two-stage method of obtaining salt from brine, which consists in subjecting an enclosed body of brine in the first stage to heat and pressure to partially evaporate the brine, thereupon in the second stage, subjecting the enclosed body of brine without the application of heat thereto toa lower pressure than that prevailing in the first stage to cause salt to freely separate out of the brine, andseparately drawing off steam from the body ofbrine in the two stages, the former at a higher pressure than the latter.

2. The hereinbefore described evaporating apparatus, which comprises in combination, a primary evaporator, a heating element therein, means for supplying fresh brine from below into said primary evaporator,an exhaust steam vent in the top of said primary evaporator and a brine colexhaust steam Vents for withdrawing the f exhaust steam from out of said two evaporaters, for compressing the withdrawn exhaust'steam and forcing it into the said primary evaporator heating element.

' ELIAS WIRTH-FREY.

7 fresh brine to said- 

